Fluorescence Sensor Based On Gold Nanomaterials And DNA Walker For Application In Environmental And Biological Analysis

With the rapid development of agricultural production,environmental safety issues represented by organophosphorus pesticides have become increasingly serious.Organophosphorus pesticides have intensive acute neurotoxicity.If they are ingested or inhaled,they will cause a series of serious health problems and endanger lives.To solve the environmental safety problem is to detect environmental pollutants,especially pollutants that are harmful and trace amounts.On the other hand,disease poses a major threat to human health and survival.Disease is one of the most important social problems faced by countries all over the world.Therefore,it is very important to develop simple,fast,and highly sensitive method for disease detection.Fluorescence detection method has been developed into an important and effective analytical method with good detection and recognition performance.Fluorescence detection method has been widely used in many fields such as environmental detection and life science.Current fluorescence analysis methods often have the following two deficiencies:（1）Only a few substances have fluorescent properties,and the disorder of the fluorescent materials causes fluorescence sensing to be interfered;（2）The application range of fluorescence detection method is narrow,called,the sensitivity is reduced.Aiming at the problems existing in the above research background,based on the new fluorescence sensing method as the main line,this paper developed the gold cluster with excellent luminescence performance,and realized the sensitive detection of environmental pollutants organophosphorus pesticides;In addition,a new fluorescence sensing method with high sensitivity for detection of Zika virus was constructed based on the fluorescence characteristics of anthocyanin Cy5,combined with 3D DNA walker and catalytic hairpin assembly isothermal nucleic acid signal amplification technology.The main contents are as follows:Chapter 1:Introduction,mainly introduces the fluorescence analysis method,the classification of fluorescent materials,fluorescence sensing method combined with DNA signal amplification technology,and briefly introduces the application of fluorescence analysis method in environmental and biological aspects.Chapter 2:Fluorescence method has the advantages of low requirements on instruments and equipment,easy operation,short detection time and high stability.In this chapter,a“off-on-off”fluorescence sensor was constructed and applied to the detection of organophosphorus pesticides.AuNCs-MnO₂ nanosheet was used as a fluorescence quenching signal molecule.By introducing enzyme to hydrolyze acetylcholine to produce thiocholine,MnO₂ nanosheets were induced to decomposition into Mn²⁺,and the fluorescence of Auncs was released.The fluorescence was quenched in the presence of organophosphorus pesticides.Under the optimal experimental conditions,the linear range of the response curve of organophosphorus pesticide concentration to fluorescence intensity was 0.05-10ng·mL^-1,and the minimum detection limit was 0.02 ng·mL^-1.Using this method,organophosphorus pesticides in river water samples have been successfully detected.The good experimental results show that this simple and rapid fluorescence sensing method has broad application prospects in environmental detection and other research fields.Chapter 3:In this chapter,a fluorescent biosensor with multiple signal amplification is constructed and applied to the detection of Zika virus.The 3D DNA Walker of DNA conjugated gold nanoparticles was synthesized firstly.The first amplification was that the 3D DNA Walker drove the DNAzyme strand to walk along the surface of the gold nanoparticles under the action of the target object Zika virus and the promoter manganese ion,which realized the efficient movement of DNA Walker.The second amplification is the use of DNA tetrahedron to achieve localized catalytic hairpin assembly,double signal amplification.Fluorescence sensing method combined with signal amplification technology has the advantages of low background signal,short experiment period,easy operation and high sensitivity detection.The method is simple to operate and has a wide kinetic detection range,and the detection limit is as low as 20 pM.The constructed fluorescence sensor has been successfully applied to the detection of Zika virus in human serum diluent,which proves that th e scheme has good reproducibility and accuracy,and can be applied to the detection of complex actual samples.